Burgess Shale

Naraoia compacta (a trilobite)

Those familiar with trilobites will be surprised when they notice that Naraoia has two body shields (cephalon and thorax) rather than the customary three carried by all others (such as Olenoides). When Walcott first discovered this fossil by splitting a Burgess Shale rock specimen, he was unaware that the two fossilized body shields effectively covered underlying soft parts. (The base of arthropod legs are important classification features.) Because of its prominent carapace (the body shield), Walcott assigned Naraoia to the Crustacea. Later, paleontologists realized that the special circumstances of the Burgess Shale permitted the specimens to be dissected into various layers. When Professor Harry Whittington examined the inner soft parts more closely, he found the distinguishing trilobite characteristics. (Our reading list cites Stephen J. Gould's book which contains a before and after photo of such a Naraoia dissection.) Fossil sizes range up to about one and one half inches.

Naraoia

The two prominent body segments are shown along with some traces of interior structures.

Naraoia compacta (Nair-OYE-yah com-PACK-tah). After the Narao lakes in Cataract Brook Canyon, above Hector, a town in British Columbia. The species name, compacta, seems self-explanatory